ClassificationAculifera is a group, with rank of subphylum, including the Aplacophora (Caudofoveata and Solenogastres) and Polyplacophora (chitons), all other molluscs being included in subphylum Conchifera (shell-bearers)(Hatscheck in Blumrich, 1891; Scheltema, 1993) or alternately including only the Aplacophora, aside with the subphyla Placophora and Conchifera (Stasek, 1972).